In our application Ser. No. 252,366, filed Mar. 25, 1981, there is described an inertial penetrator projectile which is effective against multi-plate-armored targets by virtue of the fact that the intended breakup of the penetrator increases the penetration capability of the inertial projectile. This intended breakup can be inhibited by the form-locking means which are arranged on the external periphery of the projectile in the connection zone between projectile and sabot.